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  1. #1
    Join Date
    Jan 2008
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    Thumbs down Wet insulation around chimney...

    I recently noticed water damaged drywall around my chimney.

    The chimney runs through the center of the house and is used to vent a 20 year old gas furnace and 10 year old gas water heater.

    The chimney is concrete block with clay liner. Originally I thought I had a roof leak and the moisture was coming from melting snow but once up in the attic I found moisture leaking out of the mortar of the concrete block and some block was cracking and falling off. Apparently this had been going on for sometime because the insulation around the chimney was soaked.

    To avoid the transfer of water I pulled the insulation away from the chimney and when I did that a rather large wave heat and moisture came up from the inside of the house.

    I have no idea why my chimney is bleeding water.

    I don't know whether I should reinsulate around the damaged chimney.

    Its been about 15* here lately so even if I wanted to fix whatever is damaged on the chimney I couldn't because its too cold.

    Any ideas?
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  2. #2
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
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    5,558

    Default Re: Wet insulation around chimney...

    You need to check the top of your chimney. There should be a layer of concrete around the top of the chimney, sloping to the outside that seals the opening between the block and the liner. That is probably cracked or broken away allowing water to run down between the block and the clay flue liner. You might want to take a look at this http://www.mac******.org/tech/constr...y/chimney.html
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #3
    Join Date
    Jan 2008
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    6

    Default Re: Wet insulation around chimney...

    I was on the roof this morning. There was about 12" of snow around the chimney but nothing melted away or leaking. The area you mentioned doesn't slope its flat and there was ice on there but again nothing leaking or melted. I took the cover off and shined a light down the chimney and its dry on the inside to the attic then the water starts to condense on the tile.

    Then went into the basement and pulled the water heater and furnace exhaust pipes off. It looks like whoever installed these items simply punched a hole in the clay and stuffed a pipe in there but never sealed around the clay. I'm not sure if this is standard practice or not.

    As for the water between the block and liner.. should I drill a hole in the lowest most mortar and attempt to drain it?

    Lastly what should I do about the insulation around the chimney? It was soaked so I pulled it back off the chimney but now I have a 4" air leak around the entire chimney from the attic to the basement.
    Last edited by First_Timer; 01-27-2008 at 02:50 PM.

  4. #4
    Join Date
    Jan 2008
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    6

    Unhappy Re: Wet insulation around chimney...

    Please help me with info on the insulation.

    When I pulled the insulation back from the chimney I created a 4" air leak from the attic to my basement with only the drywall on all four side preventing air flow into the rest of the house.

    To seal off the gap or reduce the cold airflow I put four sheets of partical board around the chimney. Today I crawled up there and heavy condensation on all the boards.

    What am I supposed to do?

  5. #5

    Default Re: Wet insulation around chimney...

    The 20 year old furnace is probably due for an upgrade to a condensing modern furnace that uses a pvc flu-which could be installed out of the side of the house-that would eleminate half the moisture in the chimney. the other is the hot water heater can have a power venter installed if you have the room ane 300 bucks or so and take that out of the chimney also.I know its sound expensive but if the chimney has a cracked liner ( sounds like that to me) then you would benefit with an upgrade.Combustion produces moisture -so you will have lots of it. You may need to put 2 new stainless steel liners in the chimney 1 per appliance.If everthing was new then its different but since its all old upgrades are inevitable anyway

  6. #6
    Join Date
    Jan 2008
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    6

    Default Re: Wet insulation around chimney...

    Thats what I plan on doing but right now its -40 (wind chill). I plan on waiting till spring to have both replaced. Then I'll seal off the chimney or remove it completely block by block.

    In the mean time I don't know if I should insulate around the chimney or not.

  7. #7
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,558

    Default Re: Wet insulation around chimney...

    Does your furnace, by any chance, have a 3 or 4 inch flue pipe and forced draft? If it does , it should not have been dumped into a large chimney, it should a a pipe or flue liner the same diameter going all the way up through the chimney. The newer forced draft furnaces do not supply enough draft to flush the chimney. Because of that the hot moist air goes part way up the chimney cools off and the moisture condenses. However the amount of moisture your describing seems to be a bit high. I would suggest a chimney cap that cover the entire chimney punched out for the flue pipes. That would take care of the condensation and any leaks around the cap. In the mean time I would suggest you use rigid foam insulation around the chimney until the problem is resolved. Ridged foam would at least be water proof.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  8. #8
    Join Date
    Jan 2008
    Posts
    6

    Default Re: Wet insulation around chimney...

    Thanks for the tips fellas. Time to call the furnace folks.

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